from the submitting of the original work for the article, many things have happened in the publishing world. Mainly XML is spreading its domain more and more in many areas, one of them the accessibility fields, of course.
For PDF three remarkable things could change the landscape:
- The inminent approval of PDF/UA standard as an addendum to ISO 32000-2 
- The Adobe Mars project and its downloadable plugin to convert back and forward PDF documents to XML documents => This could open many possibilities to include PDF in XML workflows 
- The CWA 15778 report , on document processing for accessibility, showing many scenarios in which PDF is included in an accessible multichannel publishing workflow
Adobe is working hard to enhance its flagship format and Adobe 9 includes the optimization of file size for PDF files, a long desired option.
Still, authoring tools fall short in their capacity to process PDF and XML for accessibility. Adobe InDesign is pushing hard against QuarkXPress for its better support to XML.
Other formats in the accessibility world have take their place: DAISY and its component DTBook , with free conversion tools from Microsoft Word and Open Office, is also pushing hard.
Will PDF maintain its niche position? the discussion is open.